Polyester composite filament yarn having stable crimps

ABSTRACT

A POLYESTER COMPOSITE MULTIFILAMENT YARN COMPOSED OF A PLURALITY OF INDIVIDUAL FILAMENTS HAVING COMBINED PROPERTIES OF THE SHRINKING PROPERTIES RESTRICTED AS FOLLOWS.   PERCENT   (1) A RANGE OF APPARENT SHRINKAGE WHEN THE YARN IS TREATED IN HOT WATER AT A STRETCHED CONDITION OF APPROXIMATELY 5 MG./DENIER 0-20 (2) SUBSTANTIAL SHRINKAGE WHEN THE YARN IS TREATED BY THE SAME MANNER AS IN CASE OF MEASURING THE APPARENT SHRINKAGE OF YARN LOWER THAN 3   THE ABOVE-MENTIONED COMPOSITE MULTIFILAMENT YARN CAN BE ALSO DEFINED WITH RESPECT TO THE DENSITY OF FILAMENT, OR NUMBER OF CRIMPS AFTER TREATMENT IN BOILING WATER. THE PREFERABLE CONDITION OF THE DENSITY OF FILAMENT IS RESTRICTED AT MORE THAN 1.3850 WHILE THE NUMBER OF CRIMPS IS RESTRICTED A RANGE FROM 10 TO 35/CM.

NOV. 2, 1971 KAZUQ TQMHTA ET AL 3,616,634

POLYESTER COMPOSITE FILAMENT YARN HAVING STABLE CRIMPS Filed June 4, 1969 United States Patent Oifice Patented Nov. 2., 1971 ABSTRACT OF THE DISCLOSURE A polyester composite multifilament yarn composed of a plurality of individual filaments having combined properties of the shrinking properties restricted as follows.

Percent (1) A range of apparent shrinkage when the yarn is treated in hot water at a stretched condition of approximately rng./ denier (2) Substantial shrinkage when the yarn is treated by the same manner as in case of measuring the apparent shrinkage of yarn Lower than 3 The above-mentioned composite multifilament yarn can be also defined with respect to the density of filament, or number of crimps after treatment in boiling water. The preferable condition of the density of filament is restricted at more than 1.3 850 while the number of crimps is restricted a range from to 35/ cm.

The present invention relates to a polyester composite filament yarn having stable crimps, more particularly a polyester composite yarn fit for use as a knitting yarn which is required to have sufiicient bulkiness and stiffness for producing knitted fabrics having superior mechanical qualities such as handling quality.

Generally, it is a well-known art that, at least two polymers having different shrinkable properties resulting from heat are used for manufacturing a composite multifilament yarn, each filament consists of the above-mentioned polymers arranged in eccentric disposition in the cross section of the filament, and when the composite multifilament yarn, which is drawn by a drawing operation, is heat-treated under a restricted low tension, very fine coil-like crimps are developed in each individual filament. In case of the present invention, the so-called side by side arrangement is included in the eccentric arrangement, and if the arrangement of the polymers is side by side and mutually adherent along the length of the filament, the above-mentioned filament of the composite yarn is remarkable. Many attempts have been made in the past to produce textile fabrics for various end uses by utilizing the above-mentioned characteristic features of the composite yarn. The knitted fabric made of the polyester composite filament yarn may be considered as a typical example. However, these knitted fabrics made of the conventional composite filament yarns have many quality drawbacks, for example, insufficient bulkiness and resilience etc. By our theoretical research and experiments in a sense of trial and error, we have found that a polyester composite multifilament yarn hereinafter described, is a suitable material for producing knitted fabrics having excellent qualities of bulkiness and resiliency.

A principal object of the present invention is to provide a polyester composite multifilament yarn eliminating the above-mentioned drawbacks of the conventional composite filament yarns.

Another object of the present invention is to provide a polyester composite multifilament yarn fit for producing knitted fabrics having a similar appearance and handling quality to a knitted fabric used in the conventional textured yarns produced by a so-called false twisting method, further, improving certain drawbacks of the above-mentioned textured yarn such as unevenness of dyeing, development of snarls in yarns during a knitting operation, degradation of luster of the knitted fabrics, and particularly to provide a polyester composite multifilament yarn having superior stretch-back property.

The term stretch-back property as used herein refers to property which, when a yarn is stretched under a tension and next the tension is released, an elongated length of the yarn caused by the tension is recovered to a certain extent. These objects and features will be apparent from the embodiments of the invention hereinafter illustrated, together with a drawing, in which:

The figure is a skeleton diagram of an apparatus for producing a crimped yarn from an undrawn composite multifilament yarn according to the present invention.

It is well-kown that the conventional composite filament is provided with crimps having substantially a coil shape. The number of coils having the direction of a right hand spiral and that of a left hand are approximately equal along the longitudinal direction of a composite individual filament. So the residual torques developed on the composite yarn will cancel each other, and the composite filament as a whole will not be provided with such residual torque which is usually present in the conventional false twisted textured filament. Generally, in the false twisting method the multifilament yarn is subjected to a large deformation caused by twisting under tension and high temperature, so that an individual filament has a deformed circular cross section and unevenness of dyeing may occur. While, in case of the composite yarns, there is no chance of large deformation caused by external forces, each individual composite filament has a uniform circular cross section and uniform dyeing property.

However, it has been understood that all composite multifilament yarns do not always provide satisfactory results for producing knitted fabrics having excellent mechanical qualities as mentioned above.

With respect to qualities of the composite multifilament yarn, a series of experimental studies have been tried to attain the present objects and we have disclosed that a suitable composite multifilament yarn for attaining the present objects can be obtained by restriction of a specific shrinkable property, shrinkage of filament and a density of yarn in the respective ranges as hereinafter illustrated.

(1) According to our study of the finishing process, knitted fabric generally is treated under a tension of almost 5 mg./ denier. However, the fabric tends to shrink in spite of treatment under tension.

By our experiment, apparent shrinkage of the knitted fabric must be restricted in a range from 0 to 20% to produce knitted fabric having excellent bulkiness and resiliency. If the apparent shrinkage of the knitted fabric exceeds 20%, the'density ofthe fabric becomes so large that the hand feeling of the finished fabric is coarse and hard.

The above-mentioned apparent shrinkage of the knitted fabric is defined and measured as follows:

The yarn is turned around a reel 10 times to form a skein by using a reeling equipment provided with a reel having 1 meter circumferential length and then a test piece having IO-meter length is made. The winding tension of the yarn around the reel is maintained at not higher than about 50 mg./ denier. The above-mentioned skein is twicefolded and is measured under an initial load 1 mg./ denier. This measured length is represented as a.

Next, the'above-mentioned twice-folded skein is treated in hot watermaintained at 98 C. for 15 minutes under a tensioirbfj mg/ denier and then the skein is put on a filter paper so as to extract water contained in the test piece, then the skein, is dried in an atmosphere without tension. The dried skein length b under tension of 1 mg./ denier is measured. By the above-mentioned measurement, the apparent shrinkage of skein in percentage is calculated by the following equation,

Apparent shrinkage (in percent) (1-g) X 100 Therefore, the above-mentioned apparent shrinkage represents shrinkage of yarn measured under a constant tension, a change of yarn length of the knitted fabrics by the finishing operation, therefore the bulkiness of the knitted fabric can be estimated by the above-mentioned apparent shrinkage of yarn.

(2) Beside the above-mentioned restriction of the characteristic features of the composite yarn, it was also found that the substantial shrinkage of the composite multifilament yarn must be restricted below 3% to attain the object of the present inv ntion, otherwise, it is impossible to expect the production of a knitted fabric having an excellent bulkiness and resiliency. It was one of the results of our experiment that if the above-mentioned substantial shrinkage of the composite multifilament yarn exceeds 3%, the density of the knitted fabrics becomes so large that the hand feeling of the fabric is very coarse. The above-mentioned substantial shrinkage of the composite multifilament yarn is illustrated as follows:

A skein is prepared in the same way as the above-mentioned measurement for the apparent shrinkage of filament and next a length of the test piece in a reel form is measured under tension of 200 mg./denier. The skein is treated in hot Water of 98 C. for 15 minutes under a tension of 5 mg./denier and dried in the same manner as the above-mentioned measurement for the apparent shrinkage of filament and next a length 1 of the dried test piece in a reel form is measured under tension of 200 mg./ denier. The substantial shrinkage of the yarn is calculated by the following equation Substantial shrinkage of yarn in percentage As mentioned above, the apparent shrinkage of yarn can be considered as a measure for estimated bulkiness of the knitted fabric in an unstretched condition while the substantial shrinkage of yarn can be considered as a measure representing bulkiness of the knitted fabric in a condition of actual use. Therefore, both properties are considered as very important factors in a sense of combination to attain the object of the present invention.

(3) As already set forth, certain finishing operations, including a dyeing operation of the knitted fabrics, are carried out normally. Therefore, even though the bulkiness of a gray knitted fabric is excellent, if this property is degraded by the above-mentioned finishing operation, it is difficult to consider that the gray knitted fabric can be used for producing a cloth having sufficient bulkiness and excellent handling quality. Besides the above-mentioned measurement of bulkiness, it was found that the condition of crimps in the composite multifilament yarn can be used as a measure for representing the bulkiness of the knitted fabric after the wet treatment with boiling water in the finishing operation. That is, if the number of crimps of the individual filament after the above-mentioned Wet treatment is so small that the bulkiness of the knitted fabric is degraded, where on the contrary, the number of crimps is so large that a density of the knitted fabric becomes very dense thereby the hand feeling of the fabric becomes very coarse. By our experiment, the above-mentioned number of crimpsmust be in a range from 10 to 35/cm. to attain the purpose of the present invention. The abovementioned number of crimps of the filament is measured by counting the number of crimps of a filament of almost 20 cm. long, under a tension of 1 mg./denier so that the number of crimps of the filament is calculated from data counted for 10 cm. length of the test piece.

(4) By our experiment, the mass density correlates remarkably with the handling quality of the knitted fabric. The mass density represents a condition of so-called crystallinity of the filament. It was found that, if the abovementioned mass density is less than 1.3850, the crimps of the filament are unstable and further, the shape of crimps is easily deformed" under low tension such as caused by the knitting operation, thereby a knitted fabric having uneven density or a knitted fabric having a similar appearance to that of filament knitted fabric having poor resiliency may be'produced. In our experiment, the abovementioned mass density was measured by a densitygradient tube at 25 C., by using normal heptane and carbon tetrachloride.

As mentioned above, by restriction of the apparent shrinkage, substantial shrinkage of the composite filament, the objects of the present invention can be attained. Further, the restriction of the number of crimps of the composite filament, or that of mass density is also important to provide the composite multifilament yarn for producing knitted fabrics having excellent qualities such as bulkiness and resiliency.

Next, an embodiment of the method for manufacturing polyester composite multifilament yarn according to the present invention is hereinafter explained. Both components are substantially polyester polymers having different intrinsic viscosity '1 that is, a component polymer having an intrinsic viscosity between 0.45 and 0.55 while another component polymer having intrinsic viscosity between 0.60 and 0.85 are preferably used. A multifilament yarn is melt spun at a temperature between 290 and 300 C. in such a way that each individual filament consists of the above-mentioned two component polymers arranged side by side and mutually adherent along the length of the filament and an arrangement of component polymers with respect to a cross section thereof is eccentric. The melt spun multifilament is taken up while being cooled by cool air with controlled temperatureand humidity so as to solidify each individual filament separatelyl Thus obtained undrawn multifilament yarn is drawn and heat-set by a drawing and heat treating apparatus provided with a heated pin and heating plates. In the above-mentioned illustration, the intrinsic viscosity n of the polyester polymer is measured in a form of O-chlorophenol solution at 25 C. and a draw ratio and relaxation ratio are defined as follows.

circumferential speed of the drawing roller Draw ratio circumferential speed of the feeding roller Relaxation ratio= X (percent) where,

Referring to FIG. 1, an undrawn composite multifilament yarn 1 is drawn by a draw ratio between 3.0 and 3.8 while passing a drawing zone between a feeding roller 2 and a drawing roller 5. In this drawing zone, a heated pin 3 maintained at a temperature between 60 and 150 C., and a heating plate 4 maintained at a temperature between 90 and 180 C., are disposed. Thus drawn yarn is supplied to a relaxation zone between the drawing roller 5 and a relaxation roller 7 so as to impart a primary bulkiness. A heating plate 6 maintained at a temperature between 50230 C. is disposed in this relaxation zone. Next, the yarn is carried to a stretch zone between the relaxation roller 7 and a tension roller 8 so as to separate the multifilaments into individual filaments. The multifilament yarn is further supplied to a relaxation zone between the tension roller 8 and another relaxation roller 9 so as to separate the multifilament yarn into individual filaments completely by a relaxation from to 30%, and next, a third heat treatment is applied to the yarn by a heating plate 10 maintained at a temperature between 150 and 240 C. while carrying the yarn in a zone between the relaxation roller 9 and a roller 11 so as to impart a secondary bulkiness and to set crimps of each individual filaments. Finally, the treated multifilament yarn is taken up onto a bobbin 12. Thus manufactured composite multifilament yarn is composed of a plurality of individual filaments having very fine crimps.

It must be understood that all combined conditions of the drawing, relaxation and heat set operations within the above-mentioned restrictions are not always suitable to produce the composite multifilament yarn of the present invention, it is rather necessary to choose a particular combination of the drawing, relaxation and heat-set operations to attain the object of the present invention, as illustrated in Examples 1 and 2 hereinafter described in detail.

With respect to the polyester polymer as a component material of the composite multifilament yarn of the present invention, the following combinations of component materials are preferably applied; terephthalic acid or its alkyl derivatives having 1 to 4 carbon atoms, with ethylene glycol; terephthalic acid or its lower alkyl derivative with ethylene glycol and at least one more other component polymer; bis(2-hydroxylethyl)terephthalate or its lower polymer; bis (2 hydroxylethyl)terephthalate and at least one more other component, and in the abovementioned combination at least 70% of the component polymers is poly(ethylene terephthalate).

The following materials are preferably used as a third component of the polymer for manufacturing the composite polyester multifilament yarn of the present invention; that is, aliphatic dicarboxylic acid such as oxalic acid, adipic acid, azelaic acid, sebacic acid; aromatic dicarboxylic acid such as isophthalic acid, phthalic acid, 2.6- naphthalene dicarboxylic acid, diphenic acid; alicyclic dicarboxylic acid such as l.2-cyclobutane dicarboxylic acid; dicarboxylic acids having sulfur or nitrogen elements such as compounds represented by the following formulas (IIOOH CIIOOH 43 COOH COOH multifunctional compound such as S-sodium sulfo isophthalic acid, methyl sulfo isophthalic acid, trimellitic acid, pyromellitic acid or its lower-alkyl ester (carbon number 1 to 4); a polyoxy compound such as a glycolester (carbon number 2 to 10), diethylene-glycol, propylene-glycol, polyethylene-glycol, butanediol, thioglycol, p-xyleneglycol, 1,4 cyclohexanedimethanol, 2,2 bis(p- 2 oxyphenyl)propane, 2,2 bis(p oxyethoxyphenyl) propane, other glycerin, pentaerythritol; p-oxyethoxyamylbenzoate, amyl p'oxymethylbenzoate; glycolic acid. Further, the following additional material may be added into the polymer for manufacturing the composite yarn according to the present invention, that is, pigment such as carbon black, phthalocyanine, titanium oxide, silicic acid; phosphorus compound such as phosphoric acid, phosphorous acid, triphenyl phosphate, trimethylphosphate, triphenylphosphate. And if a melt viscosity of the polyester is remarkably low, an additional substance such as boron compound, aluminium compound is preferably added to improve the melt viscosity of the polyester.

EXAMPLE 1 Two different polyethylene terephthalic acids having intrinsic viscosities 0.50 and 0.78 respectively are used for producing a composite multifilament yarn according to the present invention. The composite multifilament yarn composed of 24 individual filaments, having total denier 250D, is melt spun at 295 C. The undrawn multifilament yarn was treated by the apparatus shown in FIG. 1 under the following condition.

Drawing ratio between the rollers 2 and 5: 3.5 Temperature of the pin 3: 98 C.

Temperature of the heating plate 4: C.

Relaxation percentage between the rollers 5 and 7: 20% Temperature of the heating plate 6: 160 C.

Stretch percentage between the rollers 7 and 8: 20% Relaxation percentage between the rollers 8 and 9: 20% Relaxation percentage between the rollers 9 and 11: 30% Temperature of the heating plate 10: 220 C.

Thus obtained drawn composite multifilament yarn is used for producing an interlock stitched jersey and this knitted fabric is subjected to a finishing operation which is similar to that of knitted fabrics using a textured yarn produced by a so-called false twisting method. The properties of the above-mentioned composite multifilament yarn and the jersey were measured as shown in Table 1. Therefore, it was confirmed that the qualities of the above-mentioned yarn and knitted fabric were quite satisfactory for attaining the object of the present invention, further, the stretch-back property of the knitted fabric was excellent.

EXAMPLE 2 Six different composite polyester multifilament yarns were produced by applying different conditions chosen in the following ranges of factors for producing the yarn.

Intrinsic viscosity A component p0lymer0.450.55 Another component polymer0.600.85 Drawing ratio3.0-3.8 Relaxation ratios between the rollers 5 and 7, the rollers -8 and 9030% Relaxation ratio between the rollers 9 and 110-70% Temperature of the heating plate 6-From room temperature to 230 C.

Temperature of the heating plate 10150240 C.

These composite polyester multifilament yarns were used for producing an interlock stitched jersey having the same construction and weight as that of Example 1 respectively, and these fabrics were finished in the same way as that of Example 1. Qualities of these yarns and fabrics were measured as shown in Table 1. As it is clearly shown in Table l, bulkiness and resiliency of these jersey fabrics can not be satisfied as commercial goods, further, the appearance of these fabrics is also poor.

TABLE 1 Fabric Example 2 Number of erimps/em 31.7-.. 30.0 35- 22.2"... 36.5 28 34.9. Apparent shrinkage (percent) -0 -8-0 21. 3.3. Substantial shrinkage (percent) 0.2 1-9 0.0 .1... 0.3. Density (g d.) 1-3908--- 1.3841"- 1.3877-" 1.3826 1.3876. Bulkiness G0od.. Defeetiv 0d Defective.

A little defective.

Good.

Other handling qualities or hand feeling .410... Defective- .do Defective.

1 Coarse. 2 Large shrinkage in a finishing operation. 3 Defective paper like.

What is claimed is:

1. A polyester composite multifilament yarn comprising a plurality of individual filaments, each filament consisting of polymers arranged in an eccentric disposition including side by side arrangement and mutually adhered along an entire length thereof, said yarn having an apparent shrinkage in the range of 0 to and a substantial shrinkage lower than 3% when said yarn is treated in hot Water under a load of approximately 5 mg./ denier, the number of crimps developed on said filament after treatment in boiling Water being from 10 to /cm. and the density of said individual filament being more than 1.3850.

2. A polyester composite multifilament yarn according to claim 1 in which the yarn is comprised of two polyester polymers having different intrinsic viscosities, the intrinsic viscosity of one polyester polymer being in the range of 0.45 to 0.55 and the intrinsic viscosity of the other polyester polymer being in the range of 0.60 to 0.85.

3. A fabric composed of multifilamentary polyester composite yarn comprised of a plurality of filaments arranged eccentrically including side-by-side arranged polyand the density of said filament being more than 1.3850.

References Cited UNITED STATES PATENTS Breen 57140 3,365,873 1/1968 Matsumoto et al. 57140 UX 3,381,057 4/1968 Senoo et al. 161-173 UX 3,423,923 1/1969 Hume 57-140 3,454,460 7/1969 Bosley 161177 X 3,489,641 1/1970 Harcolinski et al. 161177 DONALD E. WATKINS, Primary Examiner U.S. Cl. X.R. 

